We will investigate the cellular and biochemical pathways by which bacterial peptidoglycans protect T lymphocytes from the immunosuppressive effects of glucocorticosteroid hormones. Specific characteristics of the cells which directly respond to peptidoglycans will be determined and experiments will be done to identify peptidoglycan specific receptors on these regulatory accessory cells. The functions of peptidoglycan receptor bearing accessory cells will be investigated and compared with those of accessory cells which lack such receptors. The nature of a soluble mediator (GRMF) which is produced by the peptidoglycan stimulated cells and which protects certain T lymphocytes from the glucocorticosteroids will be studied and compared with other known mediators produced by accessory cells. The subpopulations of T cells which respond to GRMF will be investigated. This work will develop experimental approaches suitable for the study of many purified bacterial adjuvants and may reveal the pathways by which bacterial substances contribute to chronic inflammatory diseases. The principal methods to be employed in this project include immunization of cultured mouse spleen cells, isolation and chemical modification of bacterial peptidoglycans, fluorescent labelling of cells and a variety of cell separation procedures.